Field of the Invention
The invention relates to a semiconductor device and a method for fabricating the same.
Description of Related Art
Among various memory products, the non-volatile memory allows multiple data writing, reading, or erasing operations, and the data stored in the non-volatile memory is retained even after power to the device is removed. Hence, the non-volatile memory has become an indispensable part to a variety of electronic products.
Generally, the non-volatile memory includes a select transistor and a plurality of memory cells. In order that the select transistor has a low operation voltage to be turned on/off easily, a thinner gate dielectric layer is usually used in the select transistor. However, the thinner gate dielectric layer cannot sustain the high voltage applied by the neighboring memory cells. If the gate dielectric layer in the select transistor is made thicker for sustaining the high voltage of the memory cells, the operation voltage would be increased. Therefore, how to keep the operation voltage of the select transistor low while enabling the select transistor to sustain the high voltage applied by the neighboring memory cells is an important issue in this field.